As a backup unit for a computer, an information recording unit able to store large-size programs and large-size data with high reliability has been developed. A magnetic tape unit is one of such units and has advantages in reliability, a storage capacity, and costs.
The magnetic tape unit mounts a magazine, and the magazine includes a plurality of cells arranged lengthwise and crosswise in a matrix form. Each of the cells houses a magnetic tape cartridge (hereinafter referred to as “cartridge”). An accessor mechanism takes out a cartridge needed at required timing from a cell housing the cartridge, and transports it to a tape drive. After completion of recording or reproducing operation at the tape drive, the accessor mechanism transports the cartridge from the tape drive to the cell from which the cartridge was taken out and inserts it into the cell.
The accessor mechanism mounting the cartridge is required to be stopped accurately in front of the cell to normally complete taking out or inserting the cartridge from or into the cell. For this reason, a drive unit for controlling a stop position of the accessor mechanism is required to preliminarily obtain coordinates of the cell, and adjust and determine the stop position of the accessor mechanism on the basis of the coordinates of the cell.
Japanese Laid-Open Patent Application JP-P2005-209280A (corresponding to US2005163022A1 and DE102005002994A1) discloses a method of adjusting the stop position of the accessor mechanism with respect to the respective cells. This method provides a positioning hole to the magazine, detects a position of the hole by using a cartridge sensor shaft included in the accessor mechanism, calculates a relative position between the position of the hole and each cell, and adjusts the stop position of the accessor mechanism.
However, we have now discovered following facts. In the adjusting method described in JP-P2005-209280A, since the positioning hole has to be provided to the magazine, a space used for making the positioning hole should be provided in the magazine. As the result, there is a problem that prevents a whole structure of the magnetic tape unit from being compact.
In addition, in the adjusting method described in JP-P2005-209280A, since a positioning adjustment is carried out by inserting the cartridge sensor shaft many times into the positioning hole, there is a problem that the adjustment requires very long time.